带锯床锯切过程的力学建模

针对带锯床锯切过程的力学问题,通过静力平衡方程和微段受力分析,提出了一种新的带锯床锯切过程力学模型,建立了初始预紧力与临界工作状态、初始预紧力与正常工作状态下各力学参量的关系.基于实验数据,验证了力学模型的正确性,研究了锯切过程中各力学参量的相互关系及影响因素.研究表明,带锯床锯切系统在锯切过程中,初始预紧力决定了带锯条的临界锯切力;正常工作过程中,带锯条紧边段拉力和松边段拉力的比值随锯切力的变化而变化;锯切过程的力学模型及相关结果为带锯床的结构设计提供了重要的理论基础.     

多晶Si太阳电池新型制绒工艺研究

提出一种采用二次酸腐蚀的多晶Si制绒新方法,首先在HF/HNO3的富HNO3体系中对Si片进行一次腐蚀,之后在富HF体系中进行二次腐蚀,以优化表面织构,减少光在Si表面的反射损失。制绒后,用扫描电子显微镜(SEM)对Si片进行了表面形貌分析,用Carry 5000紫外-可见-近红外分光光度计测量反射谱线,得到未镀减反射膜(ARC)的二次腐蚀制绒的最低反射率为20.34%,比一次腐蚀制绒(22.70%)低2.36%。将二次腐蚀新工艺应用于太阳电池工业制备中,对电池输出参量进行检测分析。结果表明,经过二次腐蚀工艺处理的太阳电池开路电压(VOC)、短路电流(JSC)和效率η均比采用一次腐蚀工艺的太阳电池有不同程度的提高,制成的太阳电池最高效率为14.93%。     

单晶硅和单晶铝纳米切削过程比较

采用分子动力学模拟方法进行了单晶硅和单晶铝纳米切削过程的比较研究．硅原子间相互作用力采用Tersoff势计算，铝原子间和工件与刀具原子间相互作用力采用Morse势计算．通过对切削过程中切屑和加工表面、能量和切削力的分析，发现硅发生非晶态相位变换和切屑体积改变，但没有位错和弹性恢复产生；而铝发生的现象却与硅相反．     

钛合金切削绝热剪切带形成过程的有限元分析

采用有限元模拟方法对钛合金切削加工中的绝热剪切带形成过程进行了研究.通过对材料本构模型、刀-屑接触摩擦、切屑分离和绝热剪切等关键物理环节建模,建立了切削加工有限元模型.利用该有限元模型模拟和分析了钛合金TC4切削绝热剪切带形成的全过程,得到了与试验相似的锯齿状切屑,切屑中绝热剪切带分布规律与试验结果较为一致,切削力模拟结果与试验数据相吻合.研究结果表明,刀尖处首先形成小的变形区并逐渐扩展至切屑表面,变形区发生集中滑移,锯齿节块滑出,最终形成变形高度集中的剪切带;绝热剪切带内的温度相当高,而其两侧材料温度较低;绝热剪切带的形成与弹性能释放密切相关,弹性模量越小,切屑锯齿化程度和剪切带间隔时间越大.     

单晶硅和单晶铝纳米切削过程比较

采用分子动力学模拟方法进行了单晶硅和单晶铝纳米切削过程的比较研究，硅原子间相互作用力采用Tersoff势计算，铝原子间和工件与刀具原子间相互作用力采用Morse势计算．通过对切削过程中切屑和加工表面、能量和切削力的分析，发现硅发生非晶态相应变换和切屑体积改变，但没有位错和弹性恢复产生；而铝发生的现象却与硅相反。     

割角法生成曲线的连续性和光滑性

本文讨论了一般割角参数下由割角法[1]所产生的折多边形簇的收敛性问题,并给出了极限曲线连续、一阶几何连续的一般条件。作为特例严格证明了[1]的结果。     

电致发光材料三芳胺聚合物的能带结构表征

采用循环伏安(CV)法结合紫外-可见(UV-Vis)吸收光谱表征了4种新型电致发光材料三芳胺聚合物TPD(PTPD)的能带结构,并对引入的基团及分子结构对其能带结构的影响进行了探讨。结果表明,从聚合物TPD和小分子TPD的UV-VIS吸收光谱的最大吸收来看,聚合后TPD的能带结构没有太大的改变。从循环伏安图看出,材料的具有较好电化学稳定性。并制成了ITO(氧化铟锡)/PTPD/Alq3(8-羟基喹啉铝)/Mg:Ag异质结电致发光器件,与典型的ITO/TPD/Alq3/Mg:Ag器件进行了比较,研究发现其器件的稳定性有的明显提高。     

Characterization of semi-coke generated by coal-based direct reduction process of siderite

Solid wastes derived from metallurgical industries pose a significant threat to environment. The utilization and disposal of these solid wastes are the major concern in the world. Semi-coke generated in coal-based direct reduction process of iron ore is a by-product and its suitable utilization is not available so far. In order to handle it properly, the characteristics of this by-product were comprehensively investigated. A series of analysis methods were used to demonstrate its mineral compositions, petrography and physico-chemical properties. The results reveal that the semi-coke has poor washability. The fixed carbon content of semi-coke reaches 76.11% and the gross calorific value is 28.10 MJ/kg, both of which are similar to those of traditional sinter coke breeze. Also, semi-coke ash possesses lower content of SiO2, Al2O3, S and higher content of CaO and MgO, which could improve the strength of sinter ore when partially substituting for coke breeze in sintering. Semi-coke features well-development porous structure and higher reaction activity, which predicts that the sintering speed could be elevated to some extent when employing it as a partial replacement of coke breeze, so the studies further suggest that the potential adverse effect of the high reactivity on sintering process could be weakened by adequately coarsening the semi-coke's particle size.     

晶体Si能带的密度泛函及第一性原理计算

针对晶体Si在二极管、三极管、晶闸管和各种集成电路中的应用与其能带结构密切相关的问题,采用密度泛函理论及第一性原理的赝势平面波方法,从理论上计算了晶体Si的电子能带.计算结果表明：Si的晶格常数为0.540nm,与实验参考值相吻合;其价带宽度为11.80eV,导带宽度为9.58eV,该结果与其他学者用OPW方法所计算的结果相符合;价带与导带之间的禁带宽度为0.80eV,进一步说明了Si是良好的半导体材料.     

Specific energy optimization in sawing of rocks using Taguchi approah简

This work aims at selecting optimal operating variables to obtain the minimum specific energy （SE） in sawing of rocks. A particular granite was sampled and sawn by a fully automated circular diamond sawblades. The peripheral speed, the traverse speed, the cut depth and the flow rate of cooling fluid were selected as the operating variables. Taguchi approach was adopted as a statistical design of experimental technique for optimization studies. The results were evaluated based on the analysis of variance and signal-to-noise ratio （S/N ratio）. Statistically significant operating variables and their percentage contribution to the process were also determined. Additionally, a statistical model was developed to demonstrate the relationship between SE and operating variables using regression analysis and the model was then verified. It was found that the optimal combination of operating variables for minimum SE is the peripheral speed of 25 m/s, the traverse speed of 70 cm/min, the cut depth of 2 cm and the flow rate of cooling fluid of 100 mL/s. The cut depth and traverse speed were statistically determined as the significant operating variables affecting the SE, respectively. Furthermore, the regression model results reveal that the predictive model has a high applicability for practical applications.     

毫秒激光辐照单晶硅产生燃烧波仿真及实验

为了研究毫秒脉冲激光作用单晶硅产生燃烧波的动力学行为,基于流体力学理论和气体动力学理论,通过建立毫秒脉冲激光辐照单晶硅燃烧波模型对燃烧波的产生及扩展运动进行仿真.结果表明,燃烧波扩展速度幅值的最大值出现在燃烧波前端附近,主要扩展方向为逆激光入射方向的径向,激光能量密度和脉冲宽度是燃烧波扩展运动行为过程中的重要影响因素,毫秒脉冲激光作用单晶硅产生燃烧波的膨胀速度会出现二次增加现象,激光损伤效果得到增强.     

Characterization and recycling of nickel- and chromium-contained pickling sludge generated in production of stainless steel

Pickling sludge generated during the neutralization of pickling wastewater with calcium hydroxide in stainless steel pickling process was characterized using X-ray fluorescence spectrometry, X-ray diffractometry, scanning electron microscopy, thermogravimetry and differential scanning calorimetry, etc. The major compositions of pickling sludge are CaF2, CaSO4, Me（OH）, （M： Fe, Cr, Ni）, and the content of CaF2 is high in the sludge. The melting point of pickling sludge is about 1350℃ and the viscosity is about 0.14 Pa.s at 1450 ℃, which are comparatively lower than those of normal refining slag. After heat treatment, the contents of sulfur and fluorine in the pickling sludge were reduced, confirming the thermal decomposition of sulfate in the sludge. Fluorine in the sludge is reduced by the gaseous SiF4 and A1F3 generated through the reactions of CaF2 with SiO2 and Al2O3. The preliminary results from the reduction test indicate that the sulfur content in the steel is not affected by the presence of sulfur in the sludge. The recovery of nickel is about 40%, and the chromium content changes marginally due to the protective atmosphere under the reduction condition of chromic oxide. The pickling sludge is a potential auxiliary material for the production of stainless steel.     

等离子切割在热切割中的地位

介绍了热切割法的种类、应用状况以及等离子切割技术的新进展,比较分析了３种热切割法的切割效率、切割质量、切割成本．在切割质量相同的前提下,从切割效率和切割成本来看,碳钢厚度为３０～５０ｍｍ以下时,用等离子切割合适,在此厚度以上时,气割合适．     

Chip-ejection interference in cutting processes of modern cutting tools

Based on the “principle of minimum energy”, the basic characteristics of non-free cutting are studied; the phenomenon and the nature of chip-ejection interference commonly existing in the cutting process of modem cutting tools are explored. A "synthesis method of elementary cutting tools" is suggested for modeling the cutting process of modem complex cutting tools. The general equation governing the chip-ejection motion is deduced. Real examples of non-free cutting are analyzed and the theoretically predicted results are supported by the experimental data or facts. The sufficient and necessary conditions for eliminating chip-ejection interference and for realizing free cutting are given; the idea and the technical approach of "the principle of free cutting" are also discussed, and a feasible way for improving or optimizing the cutting performance of modem cutting tools is, therefore, found.     

电炉炼钢厂粉尘在微波场中的升温特性

对电炉炼钢厂粉尘在微波场中的升温特性进行研究。结果表明,电炉炼钢厂粉尘对微波具有很好的吸波能力,其中不锈钢厂电弧炉粉尘在微波场中约15 min内温度就可达1000℃以上。随着微波功率的增加,粉尘表观升温速率增大。不同配碳比下粉尘的表观升温速率均较大,介于105-126℃/min之间。随着物料质量的减少,在微波场中粉尘的表观升温速率增大。粉尘颗粒粒径对表观升温速率的影响不显著。     

3%无取向硅钢薄板的表面纳米化结构与性能

为了探索金属薄板表面纳米化制备方法,本工作选取3%无取向硅钢热轧板进行表面机械研磨处理（SMAT）和异步轧制（CSR）,研究深度方向结构和硬度的变化.结果表明：SMAT过程中,3%无取向硅钢通过位错的演变,在表面形成了等轴状、尺寸约为10 nm的、取向呈随机分布的纳米晶,纳米晶层厚度约为20μm;SMAT样品经过CSR后,表面的显微组织基本不变,但纳米晶层的厚度明显减小;SMAT和CSR处理使表面硬度显著提高（约为85%）.本工作表明,SMAT与CSR复合工艺可以制备大尺寸的、具有纳米结构表层的金属薄板.     

广州市荔湾区扬尘污染现状与防控对策

根据近十年来的环境空气质量监测数据,分析了广州市荔湾区扬尘的现状和成因,探讨了该区目前扬尘污染控制中存在的问题,提出了几点防治控制对策.     

基于切削建模的螺旋铣孔刀具角度优化

针对钛合金螺旋铣孔过程中的刀具角度优化问题,固定切削参数,通过一系列实验,得到了螺旋角和前角不同的刀具产生的轴向切削力.利用遗传算法,结合Matlab程序对实验数据建立切削力模型,分析了刀具螺旋角和前角对切削力的影响,并对角度参数进行了优化.